1. Field of the Invention
The present invention relates to an image taking system, and also to an electronic-circuit-component mounting machine including the image taking system.
2. Discussion of Related Art
There is known an electronic-circuit-component mounting machine, as disclosed in JP-H08-167799A and JP-2000-124683A, in which a component-image taking system is provided to take an image of each electronic circuit component that is held by a component holding head. JP-H08-167799A discloses a component-image taking system which is equipped with a lighting device and a line sensor, and which is disposed in a fixed position located between a component supplier and a board conveyor. The lighting device includes a multiplicity of LEDs (light emitting diodes), while the line sensor includes a plurality of CCDs (charge coupled devices) arranged in a line parallel to an arrangement direction in which the component supplier and the board conveyor are arranged. The component holding head holding the electronic circuit component is moved in a direction perpendicular to the arrangement direction (in which the component supplier and the board conveyor are arranged), so that an entirety of the electronic circuit component is caused to pass over the line sensor whereby an image of the entirety of the electronic circuit component is acquired. The lighting device is configured to emit light that is adjusted depending on velocity of movement of the component holding head. Where the electronic circuit component held by the holding head has an easily recognizable and simple configuration, the component holding head is moved at an increased velocity while quantity of the light emitted by the lighting device is made large, for thereby reducing the image taking time and acquiring the image having brightness suitable for processing. Where the electronic circuit component held by the holding head has a complicated configuration, the component holding head is moved at a reduced velocity while quantity of the light emitted by the lighting device is made small, for thereby acquiring the image having brightness suitable for processing, and enabling the image to be accurately processed.
JP-2000-124683A discloses a component-image taking system which is equipped with a lighting device and a CCD camera and which is movable, by a moving device, relative to a component holding head in a direction parallel to a movement direction in which a movable body carrying the component holding head is to be moved. The lighting device includes LEDs, while the CCD camera includes a CCD and an electronic shutter. After the component holding head has received the electronic circuit component from a component supplier, the component-image taking system is moved relative to the component holding head and takes an image of the electronic circuit component. In this instance, the electronic shutter of the CCD camera allows the CCD to be exposed for an exposure time, i.e., a length of time that is dependent on a predetermined shutter speed, while the lighting device is caused to emit flashlight within the exposure time so as to illuminate the electronic circuit component. An electric current, which is supplied to each of the LEDs, is controlled such that the electric current is instantaneously supplied by an amount larger than a rated amount by which the electric current is to be supplied for causing the lighting device to be continuously lighted, whereby the lighting device is caused to emit a larger quantity of the light than where the lighting device is continuously lighted, for thereby sufficiently illuminating the electronic circuit component.